Acoustic echo can happen during a conversation via a communication network. The far end signal coming into a communication device can be played back by a loudspeaker of the communication device. A microphone of the communication device can capture both the near end signal and the output of the loudspeaker. The mixture of the near end signal and output of the loudspeaker can be transmitted back to the far end, so that a listener at the far end can receive a delayed version of his own speech as an “echo” sound.
Conventional AEC techniques work well for cancelling a linear echo from the uplink signal, while a nonlinear component of the echo is not suppressed. Use of a small loudspeaker is likely to result in a larger than usual nonlinear component in the acoustic echo. Improvements are needed for effective cancellation of the nonlinear component of the echo signal, while not adversely affecting the cancellation of the linear part of the echo.